The one best thing at Disney World

My wife and I will be going to Walt Disney World for the first time I'm 42 and she is 33. We are staying on site at the Pop Century we have 5 day pass for the parks with the hopper option what is the one best thing at Disney World we shouldn't miss? We will be there in January 2011.

Dad's that's an interesting question Answer

Wow, what a question. What is the one best thing at Disney World?. That's a toughie. There's so much.